Processed meats such as hot dogs, ham, bacon and salami contain many proven cancer-causing compounds. This has been known for many years. But people are still eating them – even people who otherwise seem to care about their health.
In this article I hope to lift the lid on just how dangerous these products are, and in doing so, cut through the uncertainty about nitrites, nitrates and nitrosamines – which are bad and which are good.
Nitrates and nitrites – what are they?
Nitrates are naturally occurring substances in plant foods. They convert to nitrites when you eat vegetables, due to bacterial fermentation on the tongue. They are harmless in plants. They are not carcinogenic. In fact, the plants highest in nitrites, rocket, kale and collard greens (not available for sale in Australia), are associated with a significant reduced risk for some cancers. Other good sources are celery and beetroot.
We need nitrates! Nitrites and nitrates are made up of two types of atoms: nitrogen (surprise!) plus oxygen.
- A nitrate contains 3 oxygen atoms (and one nitrogen atom)
- A nitrite forms when a nitrate loses one O atom, leaving 2 oxygen atoms (and one nitrogen atom)
- A further breakdown is then needed to make the nitrite into a 1-oxygen-atom nitric oxide.
Nitric oxide is vital because it sends a message to our arterial walls to relax so blood can flow freely, therefore protecting us from high blood pressure, heart disease and strokes. High nitrate foods like beetroot juice can reduce blood pressure in a matter of hours. And high saturated fat foods stop the conversion of nitrite to nitric oxide, which is one reason saturated fat causes heart disease.
Nitrate-rich plant foods (our richest source of nitrates) are also used as performance enhancing foods for sports – they increase endurance times as well as cause less oxygen to be needed during intense exercise.
Nitrites are added to cured meats because they help prevent the growth of the botulism bacteria, which causes paralysis. These nitrites ‘fix’ the colour in the meat, keeping it pink.
What is the problem with nitrites then?
The problem comes when nitrates are
- added to a product that contains a lot of amino acids (that is, a high protein food like meat),
- or are put in the presence of high heat in the absence of phytochemicals (plant micronutrients).
Under such conditions, they convert to nitrosamines which are known human carcinogens.
This conversion can occur in one of three places:
- in the meat itself (a product high in amino acids), through the salting, pickling or smoking processes of producing cured meats.
- in your stomach along with the meat you’ve eaten, or
- in a burning cigarette.
These new compounds are so carcinogenic that the American Institute for Cancer research said in 2011 that we should not just cut back on eating these processed meats, but actually “AVOID …. ham, bacon, salami, hot dogs and sausages*”. Even the smell of sizzling bacon damages lung-DNA.
All fresh meat – beef, chicken and pork – contains some nitrosamines – but not as much as processed meats like sausage, and particularly hot dogs. (*Note: this ‘sausage’ is not the type where the butcher minces fresh meat and adds binders and seasonings; these are the cured sausages that you see hanging in windows of delicatessens – the traditional Eastern European food.)
Meat-eaters can lessen nitrosamines exposure by cooking bacon at lower temperatures and never eating burnt bacon – the higher the temperatures, the more nitrosamines.
But what about the protein in plant foods? Why do they not cause their own nitrites to become nitrosamines? Because plant foods are not only lower in protein than animal foods, but are also higher in Vitamin C and anti-oxidants. These block the formation of nitrosamines in the body.
Today, many processed meat manufacturers add Vitamin C to their cured meats to minimise the development of these toxic substances. This is an improvement over the ham and bacon of 40 years ago, but it does not remove all of these dangerous compounds.
‘Nitrite-free’ meats are also available today. However, since these carry such a significant risk of botulism, they actually contain nitrate-rich celery salt or celery juice by law. As expected, once these nitrates contact the amino acid-rich meat, nitrosamines form – and often in larger quantities than with the usual nitrate treatment. Don’t be deceived!
Nitrosamines in cigarettes
Lighting a cigarette causes the conversion of the nitrates in the tobacco into these carcinogenic nitrosamines. This is harmful for 3 groups of people:
- the smoker
- the person who is with the smoker (passive smoking)
- the person who smelled the smoke on the smoker’s clothes, in the hotel room curtains, on the taxi upholstery (third hand smoke)
Residual smoke sticks to walls and fabrics. Over 80% of these nitrosamines remain in an enclosed space after the smoker has left the area. Smoking indoors endangers others – because of the power of these nitrosamines to cause cancer. Nitrosamines are so dangerous, it is with good reason that cigarette smoking is banned from many public places now.
Nitrosamines’ last stand
There is one place, however, that nitrosamines are not banned –
One hot dog (or ‘battered sav’) contains as many nitrosamines as 4 cigarettes.
Would you let your child smoke 4 cigarettes at a birthday party?
Of course not?
But they are at much higher risk of certain cancers by eating a hot dog at the show. When my children were little, butchers used to hand children a free mini hot dog (frankfurt) while I was selecting meat (back in the day when I ate meat). Typical children’s party food includes mini-hot dogs dipped in tomato sauce (“Would you like cancer with that, anyone?”).
The cancers caused by these processed meats are kidney and stomach cancers in adults, brain tumours and childhood leukaemia in children. Even as cigarette smoking rates have dropped in the West in the last few decades, these cancer rates have risen – most likely due to meat consumption having increased overall.
So don’t fear nitrates and their cousins, nitrites – these are beneficial and necessary substances for health, found in plants. The problem is only with the nitrosamines they convert to when heated or added to meat.